U.S. patent number 3,963,295 [Application Number 05/570,128] was granted by the patent office on 1976-06-15 for heat-shrinkable molded high voltage connector.
This patent grant is currently assigned to AMP Incorporated. Invention is credited to Jan Philip Askman, George Warren Wolverton.
United States Patent |
3,963,295 |
Askman , et al. |
June 15, 1976 |
Heat-shrinkable molded high voltage connector
Abstract
The invention relates to an electrical connector for a high
voltage electrical lead terminated to an electrical contact and a
method for making the same wherein the connector includes a
silicone rubber receptacle insertably receiving and surrounding the
contact to prevent arcing thereof together with a dielectric tube
having a section secured within the receptacle and being pre-shrunk
to conform in shape to that of the electrical contact. A
heat-shrinkable section of the tube projects from the receptacle
and is heat-shrinkable to conform sealably around the electrical
lead.
Inventors: |
Askman; Jan Philip (Carlisle,
PA), Wolverton; George Warren (Elizabethtown, PA) |
Assignee: |
AMP Incorporated (Harrisburg,
PA)
|
Family
ID: |
24278362 |
Appl.
No.: |
05/570,128 |
Filed: |
April 21, 1975 |
Current U.S.
Class: |
439/276; 439/730;
439/281; 439/932 |
Current CPC
Class: |
H01R
13/53 (20130101); Y10S 439/932 (20130101) |
Current International
Class: |
H01R
13/53 (20060101); H01R 013/52 () |
Field of
Search: |
;339/59-61,89,94,101,DIG.1 ;174/DIG.8 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McGlynn; Joseph H.
Attorney, Agent or Firm: Kita; Gerald K.
Claims
What is claimed is:
1. An electrical connector, comprising:
a molded silicone rubber portion having a cavity therein,
a sleeve of heat-shrinkable material having a first section molded
into said cavity of said silicone rubber portion, said first
section being pre-shrunk to conform to the surface irregularities
of an electrical contact, and
said sleeve having a relatively enlarged heat-shrinkable second
section integral with said first section and protruding from said
silicone rubber portion and being heat-shrinkable to conform
sealably in encirclement over an insulation covered wire terminated
to said contact.
2. The structure as recited in claim 1 wherein, the interior of
said second section is provided with a sealant coating.
3. The structure as recited in claim 1, and further including:
a rigid shell receiving said silicone rubber portion,
a flange on said silicone rubber portion, and
a ring received over said flange and secured removably to said
shell.
Description
BACKGROUND OF THE PRIOR ART
This invention relates to a field installable connector for high
voltage leads. It is often desirable to provide a high voltage
electrical lead with a connector which is readily assembled from
its component parts and installed on the lead without a need for
special tooling or complex assembly procedures. A desirable
assembly procedure would involve terminating the electrical lead
with an electrical contact and then inserting the terminated lead
and contact within the confines of a connector having suitable
dielectric properties adequately protecting the contact and
terminated lead from arcing, whether the connector is mated or in a
unmated condition, and wherein the connector also suitably conforms
sealably in encirclement over the terminated lead and contact.
SUMMARY OF THE INVENTION
The present invention achieves the above stated objectives sought
in the prior art by providing a molded silicone rubber dielectric
sheath or receptacle which is molded to conform in shape to an
insertable electrical lead. The receptacle is molded integrally
with a dielectric tube having a first section molded and secured
within the receptacle and also conforming in shape to that of an
insertable electrical lead. The tube further includes a
heat-shrinkable section projecting outwardly from the receptacle
and having a diameter relatively large enough to permit free
insertion of the contact and high voltage electrical lead
terminated with the contact. The heat-shrinkable section is then
shrunk in sealing conformation over the lead. The tube section
which is molded within the receptacle is advantageously pre-shrunk,
for example, over a mandrel to achieve the desired shape of
conformation to that of the electrical contact.
OBJECTS
It is accordingly an object of the present invention to provide an
electrical connector for a high voltage electrical lead terminated
to an electrical contact, the connector having a dielectric sheath
forming a receptacle for insertably receiving and surrounding the
contact and a dielectric tube secured to the sheath and
heat-shrinkable for sealed encircling conformation on the lead.
Another object of the present invention is to provide a silicone
rubber receptacle for an electrical contact with an integral
dielectric tube which is heat-shrinkable to conform sealably around
an electrical lead and wherein a section of the tube is secured
with the receptacle and is preshrunk to conform in shape to that of
the electrical contact which is terminated to the lead and then
freely inserted within the receptacle.
Another object of the present invention is to provide an electrical
connector with a heat-shrinkable dielectric tube having a
receptacle section which is pre-shrunk to conform in shape to that
of an insertable electrical contact and which is molded within a
dielectric sheath forming a receptacle surrounding the contact to
prevent arcing thereof.
Another object of the present invention is to provide a method for
making an electrical connector having a dielectric portion molded
to a pre-shrunk section of a tube having a heat-shrinkable section
projecting from the dielectric portion.
Another object of the present invention is to provide a method of
making an electrical connector for a high voltage electrical lead
terminated to an electrical contact wherein the connector includes
a dielectric receptacle for the contact with an integral dielectric
tube which is heat-shrinkable to conform sealably around an
electrical lead and wherein a section of the tube is secured in the
receptacle and is pre-shrunk to conform in shape to that of the
electrical contact which is terminated to the lead and freely
insertable within the receptacle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an enlarged fragmentary perspective of a preferred
embodiment of the present invention with the component parts
thereof illustrated in partially assembled configuration.
FIG. 2 is an enlarged fragmentary elevation in section illustrating
the fully assembled component parts of the embodiment shown in FIG.
1.
FIG. 3 is an enlarged fragmentary elevation in section illustrating
the manufacture of selected component parts of the connector
according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With more particular reference to FIGS. 1 and 2, there is shown
generally at 1 a preferred embodiment of a connector according to
the present invention. The connector includes a sleeve or sheath 2
of dielectric such as silicone rubber molded to an elongated
tapered sleeve or tubular configuration at its forward portion 4.
An integral externally projecting annular collar or flange 6 is
formed between the forward portion 4 and a rearward cylindrical
portion 8 of the sheath 2. The sheath includes an internal
generally cylindrical cavity 10 terminating at a forward end wall
12 provided therethrough with an aperture 14 of reduced diameter
and in alignment with and communicating with the cavity 10. The
connector further includes an elongated tube or sleeve 16 of
heat-shrinkable dielectric having a forward section 18 secured
within the sheath 2. An internal opening 20 throughout the length
of the tube thus is in alignment with and communicates with the
cavity 10. A rearward section 24 of the tube 16 projects outwardly
of the rearward end portion 8 of the sheath. An electrical lead is
shown generally at 26 and includes an electrical conductor or wire
28 provided thereover with an encircling sheath of insulation 30
such as silicone rubber. It is to be understood however that any
suitable dielectric such as Teflon also may be used as the
dielectric sheath 30. A portion of the sheath 30 is stripped away
to expose an end portion of the conductor 28. The exposed conductor
28 is then terminated with an electrical contact generally
illustrated at 31. The contact includes a rearward portion 32 which
is generally cylindrical and hollow to form a wire barrel
insertably receiving the exposed end portion 28 of the conductor
28. The conductor is terminated to the wire barrel portion by
crimping at 34. The contact 30 further includes an elongated hollow
cylindrical forward end portion 36 with an external integral
annular collar 38 between the rearward portion 32 and the forward
portion 36.
In the assembly of the device, the lead 26 is terminated with the
contact 30 as described. The terminated lead and contact are then
coated thereover with a thin layer of a suitable dielectric
adhesive such as silicone RTV. The contact and terminated lead are
then freely insertable through the end 38 of the tube 16 until the
cylindrical forward end portion 36 of the contact 30 registers
within the cavity 10 and is seated against the bottom wall 12 of
the sheath 2. It is noted that the tube interior initially is
larger than the transverse dimensions of the contact and lead. The
length of the contact is entirely within the confines of the sheath
2 which serves as a receptacle freely insertably receiving the
contact 30 therein. The forward portion 4 of the sheath 2 may be
molded rather precisely in conformity and in encirclement around
the forward portion 36 of the contact 30. In addition the sheath 2
may be molded from silicone rubber which is highly rubbery, soft
and resilient in order to freely receive the insertable contact 30
and yet readily conform to the outer periphery thereof. The end
wall 12 insures surrounding of the contact with the dielectric
sheath to prevent touching or close proximity of the contact with
any object across which an arc might be substained when the lead is
energized and when the connector is in either its mated or unmated
condition. It is further noticed that the forward end portion 18 of
the tube 16 is of reduced diameter with respect to the
heat-shrinkable rearward end portion 24 thereof. The forward
portion 18 may be pre-shrunk into conformity with the anticipated
external shape of the insertable contact 30 prior to securing of
the forward end portion 18 within the sheath 2. Since the forward
end portion 18 is not as resilient as the silicone rubber sheath 2,
there is anticipated that some clearance or space 40 will occur and
be defined between the contact 30 and the inner wall 20 of the
forward end portion 18 of the tube 16. However such clearance or
space will become filled with the silicone RTV 42 which has been
coated on the terminated contact 30 prior to its insertion within
the connector. More particulary the silicone RTV 42 applied to the
contact 30 in liquid form serves as a lubricant permitting
insertion of the contact within the sheath 2. Such insertion
procedure causes extrusion of the liquid silicone RTV into the
clearance 40 thus filling the clearance 40 thereof. Upon curing the
silicon RTV will remain solidified in the clearance further serving
as a dielectric intending to sealably conform to the shape of the
contact 30 and the exposed conductor 28. The rearward portion 24 of
the tube 16 is then shrunk into sealed conformity and in
encirclement around the terminated lead. Some of the silicone RTV
will remain within the confines of the rearward portion 24 of the
tube 16 and will thereby serve as a sealant upon curing. However if
desired, the rearward portion 24 may also be provided with a
sealant coating on the interior defining the opening 20 thereof
prior to insertion of the terminated lead and contact 30. The
sealant may be heat meltable to provide a sealant which flows when
the tube is heat shrunk. To complete the assembly, the sheath 2 may
be inserted within a complementary tapered recess 44 of a rigid
dielectric shell 46. A rearward portion 48 of the shell is
externally threaded and forms a seat against which the collar 6 is
seated. A stepped annular ring 50 is freely received over the
rearward portion 8 and over the exposed part of the collar 6 which
projects outwardly of the rearward portion 48 of the shell. An
enlarged ring 52 having a radially inward directed annular flange
54 captures the enlarged part of the stepped ring 50. A forward end
portion of the ring 52 is internally threaded at 56 and is
threadably advanced over the rearward end portion 48 of the shell
46. The annular collar 6 of the sheath 2 is thereby compressed
between the stepped ring 50 and the rearward portion 48 of the
shell 46 thereby forming a seal at the interface between the shell
46 and the dielectric sheath 2. As shown the connector 1 includes
only a single terminated lead 26. It is however to be understood
that the shell 46 may be provided with any desired number of
cavities 44 into which may be connected a corresponding plurality
of leads 26 to form a multiposition connector 1.
With more particular reference to FIG. 3, the manufacture of the
sheath 2 and tube 16 will be described in detail. It was found
advantageous that the tube 16 be cut to selected length from a tube
of heat-shrinkable material which would allow pre-shrinking of the
forward portion 18 thereof without damaging the heat-shrinkable
properties of the rearward portion 24 thereof. This would allow the
forward portion 18 to be pre-shrunk over a mandrel 58 separately
from the subsequent shrinking of the rearward portion 24 in
conformity over the lead 26. Such a material was found to be a
commercially available silicone shrinkable material. The mandrel 58
is provided with an enlarged cylindrical rearward portion 60 having
a diameter which is larger than the diameter of the insulation 30
and which retains the rearward portion 24 of the tubing in its
radially expanded configuration in order to retain the
heat-shrinkable properties thereof. The mandrel portion 60 is
stepped down to a relatively reduced intermediate diameter portion
62 which in turn is stepped down to an elongated reduced
cylindrical portion 64, in turn stepped down to a reduced diameter
tip 66. As shown in FIG. 3 the forward portion 18 of the tube 16
completely encircles the portion 62 of the mandrel and partially
encircles the portions 64 and 60 of the mandrel. The forward
section 18 of the tube 16 is then shrunk by the application of heat
to conform to the mandrel portions 62, 64 and 60. The portion 62 of
the mandrel is of an outer diameter conforming to the outer
diameter of the collar 38 of the contact 30. The mandrel portion 64
is of a diameter and length conforming or corresponding to that of
the portion 36 of the contact 30. Thus the tube section 18 is
pre-shrunk in conformity with the outer dimensions of an electrical
contact expected to be inserted within the tube 16 and therefore
within the connector 1. The mandrel 58 together with the section 18
of the tube 16 is then located between a pair of molding dies 68
and 70 which close together at a parting line 72. Each of the die
portions 68 and 70 are provided with corresponding mating cavities
74 and 76 into which is injected silicone rubber 78 which forms the
forward portion 4, the rearward portion 8 and the collar 6 of the
sheath or receptacle 2. The silicone is thus injection molded
around the corresponding mandrel portions to form the end wall 12,
the aperture 14 and the internal cavity 10. In addition the
silicone rubber is injection molded around the pre-shrunk section
18 of the tube thereby integrally molding the sheath or receptacle
portion 2 to the section 18 of the tube 16.
Upon removal of the component parts 2 and 16 from the dies,
followed by removal of the mandrel 58, the completed sheath or
receptacle 2 and tube 16 is suitable for assembly into the
connector 1. Due to the resiliency of the silicone, the collar 38
can be force-fit within the sleeve section 18, creating the
distortion thereof as shown in FIG. 2.
According to a modification of the process, the rearward end
portion 8 of the silicone receptacle may be fabricated from a ring
or a wrapped ribbon of silicone encircling the sleeve section 18
which has been pre-shrunk into conformity with the mandrel portion
62. The ring or ribbon thus forms a silicone insert placed with the
sleeve section 18 within the dies 68 and 70. When the remainder of
the silicone receptacle is injection molded, the insert then
becomes fusibly joined to the injected silicone to form a unitary,
one-piece silicone receptacle 2.
What has been shown and described is a preferred embodiment of the
present invention. Other modifications and embodiments of the
present invention which would be apparent to one having ordinary
skill in the art are intended to be covered by the spirit and scope
of the appended claims.
* * * * *